Ohio kidnapper Ariel Castro found dead in prison cell

Ariel Castro, the Ohio kidnapper sentenced to serve life in prison after holding three women hostage for a decade, has been found dead in his prison cell.

Castro had been sentenced to life plus more than 1,000 years for the kidnap and repeated abuse of Amanda Berry, 27, Gina DeJesus, 23, and 32-year-old Michelle Knight.

The 53-year-old was being held at the Correction Reception Centre in Orient, Ohio.

The former school bus driver, who was under protective custody and isolated from other inmates, was found hanging in his cell at about 9:20pm Tuesday (local time) when prison staff were making their rounds, rehabilitation and correction department spokesperson JoEllen Smith said.

Prison medical personnel tried to resuscitate him and he was transferred to a local hospital but pronounced dead about 90 minutes later, Ms Smith said.

One condition of his protective custody was that prison staff had to check on him every 30 minutes at staggered intervals, a department of corrections statement said.

Castro received his life sentence in early August after agreeing to a plea deal that saw him avoid the death penalty.

"I'm not a monster. I'm sick," he pleaded.

Despite having pleaded guilty to 977 charges related to his victims' brutal decade-long ordeal, including many rapes and the murder of a foetus through beating its mother, Castro said he was not a violent man.

He said he had himself been sexually abused as a child and had grown up obsessed with sex.

Castro said he had not plotted the three kidnaps, but had acted on impulse.

"I am not a monster. I am a normal person. I am just sick. I have an addiction just like an alcoholic has an addiction," he said.

Castro was arrested in early May after his neighbour Charles Ramsey came to the rescue of Ms Berry, who was trying to escape the house.

Rescued along with the three women was Ms Berry's six-year-old daughter, fathered by Castro and born during her mother's captivity.

In what was one of the most sensational US crime stories in recent memory, Americans were elated by news that the three women had been found alive and freed but were stunned by the circumstances of their ordeal.

Suicide note dismissed as an attempt to blame victims

Castro had been imprisoned since August 5 at the Ohio centre, a prison processing facility outside Columbus, the state capital.

He was to remain there while undergoing a series of mental and physical evaluations before being transferred to a more permanent lock-up, prison officials said.

"A thorough review of this incident is under way and more information can be provided as it becomes available, pending the status of the investigation," Ms Smith said.

Cuyahoga County prosecutor Tim McGinty acknowledged after Castro's sentencing that a suicide note and confession written by Castro had been found by authorities at his residence when they searched his home following his arrest in May.

But Mr McGinty dismissed the letter as an attempt by Castro, whom he described as a "narcissist", to feel sorry for himself and to place blame on his victims.

The house where the three women were held and bound with chains and ropes for periods of time has since been torn down along with two homes on adjacent lots.